The socket head cap screws are made of high quality stainless steel 304 which offers chemical and corrosion resistance. | Thread Diameter: 6 mm; Pitch Size: 1.0 mm. Thread Length: 20 mm, 25 mm, 30 mm, 35 mm, and 40 mm. | Head Diameter: 10 mm; Head Height: 6 mm; Drive Type: Allen Hex Socket 5 mm; Color: Silver Tone. | Package Included: M6 x 20 mm (10 PCS), 25 mm (10 PCS), 30 mm (10 PCS), 35 mm (10 PCS), 40 mm (10 PCS), and all come in a quality plastic storage box. | Socket Head Cap Screws are great to have around for use in wood and wet environments.